Burglar-alarm



(No Model.)

P. H. NEAL & J. R. DONNELLY.

BURGLAR ALARM.

No. 480,340. Patented Aug. 9, 1892.

N ITED QTATES PATENT OFFICE.

FRED H. NEAL AND JOHN R. DONNELLY, OF FAIRFIELD, MAINE.

BURGLA SPECIFICATION forming part of Letters Patent No. 480,340, datedAugust 9, 1892.

Application filed March '7, 1892. Serial No, 424,030. (No model.)

To all whom it may concern:

Be it known that we, FRED lil. NEAL and JOHN R.-DONNELLY, citizens ofthe United States, residing at Fairfield, in the county of Somerset andState of Maine, have invented certain new and useful Improvements inBurglar-Alarms; and we do hereby declare the following to be a full,clear, and exact description of theinventiomsuch as will enable othersskilled in the art to which it appertains to make and use the same.

Our invention relates to a device to be ap'- plied to an electricalarm-circuit such as is connected with the doors or windows of build-1n gs to ring an alarm when such doors or windows are opened. As thosealarms have hitherto been constructed the dooror window on being openedcompleted the alarm-circuit which started the alarm-bell ringing, thebell continuing to ring until the door or window was closed. Thecontinued ringing was very annoying when the alarm was accidentally setoff.

The object of our invention is to limit the ringing of the alarm to ashort-time while the door or window is being opened and closed and toprevent the continuous ringing above described.

The invention consists of an elliptical spring placed with its concaveportion in the line of motion of the door or window and electricallyconnected with one pole of an alarm-circuit and an arm adjacent to saidspring in connection with the other pole of said circuit, the partsbeing so located with reference to the door or window that as they passby said spring it will be pushed into contact with said arm and socomplete the circuit.

In the accompanying d awings we have represented a door provided withour device.

Figure lis a section on x 00 of Fig. 2. Fig. 2 is a front View of ourattachment. Fig. 3 is a section on 'y y of Fig. 2.

A represents the upper end of a door, and B is the casing directly abovesaid door.

The parts of our device are secured to a baseboard 0, which is attachedto the casing directly above thetop of the door, as here shown, by meansof screws 0 c. The elliptical spring E, on which the door acts, is bentup at the end to form a flange, by which it may be attached to thebase-board. The main portion forms an arm which projects outward, theconvex portion of the spring extending downward into the line of motionof the door, so that the latter as it opens will press the spring upwardas it passes under. Directly above the spring E is an arm D, bent at theend in the same manner as the spring E and secured to the board bybinding-screws f g, which pass through the arm D and the spring E. Boththe arms D and the spring E are made of some good conducting material,such as brass or steel, by which an electrical current can be conducted.The bent portion of the spring E is connected electrically with one poleof an alarm-circuit and the arm D is connected with the opposite pole,the arm and the spring being insulated from each other by a layer ofinsulating material I. This we accomplish as follows: The binding-screwg is connected with the binding-post r in the usual way by means of awire (1, held between the head of the screw and the metal washer Z.Between the washer and the arm D is an insulated washer '2 The inner endof the screw passes through a metal washer m, which is held between theboard and the spring E. The opening through the arm D, around the screwg, is filled with insulating material, so that the screw is inelectrical connection with the wire (I and with the spring E, but isinsulated from the arm D. In like manner the binding-screwf is connectedwith the arm D and the binding-post O by means of the wire 6. The wire 0is held between the head of the screw and the metal washerj, which is incontact with the arm D. The inner end of the screw is insulated from thespring E by a washer n of insulated material, which extends up into theopening in the spring E, through which the screw passes. Thebinding-post O is connected with one of the wires 1) of analarm-circuit, and the hinding-post r is connected with the other wirea.

The operation of our device is evident from its construction. When thedoor swings under the elliptical spring E, the spring is for the momentpressed into contact with the arm D, whereby the alarm-circuit iscompleted and the bell caused to ring. The current passes through thearm a, supposing this to be the negative wire, thence over the wire (Zto the top of the screw g, down the screw g to the spring E, thence tothe armD at the point where the two are held in contact by the door,thence through the screwf, wire t, binding-post O to the positive wireb, whence it passes through the alarm-circuit to the wired and c.

It is evident that the device may be secured on the casing at the sideof the door instead of at the top, and it can also be placed on thecasing of a window in the line of motion of the same.

We claim- The herein-described electric alarm, consisting of anelliptical spring and an arm held adjacent to each other, each havingits end turned up at right angles to form a flange,

